Question: Simplify the following expression: $r = \dfrac{-7}{10a} + \dfrac{1}{10a}$
Since the expressions have the same denominator we simply combine the numerators: $r = \dfrac{-7 + 1}{10a}$ Combine like terms: $r = \dfrac{-6}{10a}$ Simplify by dividing numerator and denominator by 2: $r = \dfrac{-3}{5a}$